This invention is directed to improved structure for a telephone rotary dial apparatus. A rotary dial as is well-known provides control of the call direction in telephone systems. As such, the dial is mounted in a telephone station instrument and provides a visual annular number plate and finger wheel in a well-known manner. The rotatable finger wheel is affixed to the operative mechanism through the center of the dial, the operative mechanism being disposed on the rear of a dial mounting base for outpulsing in response to the rotary movement of the finger wheel.
Most dial bases have been manufactured of stamped and plated steel with the operative components mounted by screws or rivets to the base and with portions of the metal base suitably formed or bent at various angles to produce the desired functions. Twin metal plates are frequently necessary to provide the plural mounting members necessary. Recently, dial bases have been fabricated of molded high impact plastics such as that sold under the trade name "Lexan." With such plastic dial bases, some of the mounting members may be molded into the base. The base receives the operative mechanism and the face or number plate. The number or indicia plate which may include a single integral ring or plural rings should be readily capable of mounting on the dial base in a predetermined angular position relative to the operative mechanism and should be able to be readily secured in this position. Frequently this mounting is performed through the use of screw receiving embosses mating with an opening for suitable screw fastenings.
In any such dial, certain basic requirements must be met. For example, the number plate must be stationary relative to the base and operative mechanism. A finger wheel should be mounted on the exterior of the number plate, the finger wheel being rotatable under manual control. The finger wheel must be connected to the operative dial mechanism within a central opening in the dial base, the mechanism being mounted on the back side of the base. With the dial fully assembled, the dial must then be capable of being secured within the necessary telephone instrument housing.
Of the more recent dials using a molded plastic dial base, an exemplary one is shown in the article by C. Ciborra on Page 56 of "Electrical Communication" (Technical Journal published by International Telephone and Telegraph Corporation), Vol. 46 (1971) Number 1.
In the dial shown by that article, molded bosses and threaded receivers provide for mounting the various components and assemblies to the dial base.